Conventionally, acknowledge back communication systems include a terminal for transmitting messages. Portable units receive the messages and acknowledge message reception by sending acknowledgment signals (ACKs) back to the terminal. Therefore, the terminal can determine whether or not a transmitted message was actually received by a portable unit.
Recently, communication systems have been developed in which a portable unit additionally transmits a "read" acknowledgment signal (READ ACK) to the terminal in response to presentation of a received message to a user. The message originator can then be informed when the user has read the message.
When the user postpones reading or responding to a received message for an indefinite period of time, the originator can discover that the user has not yet read the message because a READ ACK will not have been received by the terminal. However, the only ways to notify the user that he should read the message are by transmitting another duplicate message or by tracking the user down through alternative means, such as by telephone or electronic mail. These methods, even if effective, waste time during which the originator must provide duplicate information to the terminal, call the user, or transmit an electronic mail message to the user. Retransmission of the message could also result in inefficient use of the system. For instance, if the message is an information message of substantial length, sending the message again wastes system capacity and result in longer latency for other user messages being delivered by the system.
Thus, what is needed is a method and apparatus for reminding the user of unread messages or of messages that are awaiting a response.